golang
diff --git a/‎html/escape.go‎
Lines changed: 1 addition & 1 deletion b/‎html/escape.go‎
Lines changed: 1 addition & 1 deletion
diff --git a/‎html/parse.go‎
Lines changed: 17 additions & 4 deletions b/‎html/parse.go‎
Lines changed: 17 additions & 4 deletions
diff --git a/‎html/parse_test.go‎
Lines changed: 25 additions & 0 deletions b/‎html/parse_test.go‎
Lines changed: 25 additions & 0 deletions
@@ -299,7 +299,7 @@ func escape(w writer, s string) error {
 case '\r':
 esc = "&#13;"
 default:
-panic("unrecognized escape character")
+panic("html: unrecognized escape character")
 }
 s = s[i+1:]
 if _, err := w.WriteString(esc); err != nil {
 
@@ -231,7 +231,14 @@ func (p *parser) addChild(n *Node) {
 }
 
 if n.Type == ElementNode {
-p.oe = append(p.oe, n)
+p.insertOpenElement(n)
+}
+}
+
+func (p *parser) insertOpenElement(n *Node) {
+p.oe = append(p.oe, n)
+if len(p.oe) > 512 {
+panic("html: open stack of elements exceeds 512 nodes")
 }
 }
 
@@ -810,7 +817,7 @@ func afterHeadIM(p *parser) bool {
 p.im = inFramesetIM
 return true
 case a.Base, a.Basefont, a.Bgsound, a.Link, a.Meta, a.Noframes, a.Script, a.Style, a.Template, a.Title:
-p.oe = append(p.oe, p.head)
+p.insertOpenElement(p.head)
 defer p.oe.remove(p.head)
 return inHeadIM(p)
 case a.Head:
@@ -2324,9 +2331,13 @@ func (p *parser) parseCurrentToken() {
 }
 }
 
-func (p *parser) parse() error {
+func (p *parser) parse() (err error) {
+defer func() {
+if panicErr := recover(); panicErr != nil {
+err = fmt.Errorf("%s", panicErr)
+}
+}()
 // Iterate until EOF. Any other error will cause an early return.
-var err error
 for err != io.EOF {
 // CDATA sections are allowed only in foreign content.
 n := p.oe.top()
@@ -2355,6 +2366,8 @@ func (p *parser) parse() error {
 // <tag>s. Conversely, explicit <tag>s in r's data can be silently dropped,
 // with no corresponding node in the resulting tree.
 //
+// Parse will reject HTML that is nested deeper than 512 elements.
+//
 // The input is assumed to be UTF-8 encoded.
 func Parse(r io.Reader) (*Node, error) {
 return ParseWithOptions(r)
 
@@ -517,3 +517,28 @@ func TestIssue70179(t *testing.T) {
 t.Fatalf("unexpected failure: %v", err)
 }
 }
+
+func TestDepthLimit(t *testing.T) {
+for _, tc := range []struct {
+name string
+input string
+succeed bool
+}{
+// Not we don't use 512 as the limit here, because the parser will
+// insert implied <html> and <body> tags, increasing the size of the
+// stack by two before we start parsing the <dl>.
+{"above depth limit", strings.Repeat("<dl>", 511), false},
+{"below depth limit", strings.Repeat("<dl>", 510), true},
+{"above depth limit, interspersed elements", strings.Repeat("<dl><img />", 511), false},
+{"closing tags", strings.Repeat("</dl>", 512), true},
+} {
+t.Run(tc.name, func(t *testing.T) {
+_, err := Parse(strings.NewReader(tc.input))
+if tc.succeed && err != nil {
+t.Errorf("unexpected error: %v", err)
+} else if !tc.succeed && err == nil {
+t.Errorf("unexpected success")
+}
+})
+}
+}
Original file line number	Diff line number	Diff line change
`@@ -299,7 +299,7 @@ func escape(w writer, s string) error {`
`299`	`299`	`case '\r':`
`300`	`300`	`esc = " "`
`301`	`301`	`default:`
`302`		`-panic("unrecognized escape character")`
	`302`	`+panic("html: unrecognized escape character")`
`303`	`303`	`}`
`304`	`304`	`s = s[i+1:]`
`305`	`305`	`if _, err := w.WriteString(esc); err != nil {`